perf(semantic): resolve_references_for_current_scope without a temp Vec#22599
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## Summary Adds `kitchen-sink.tsx` — a comprehensive synthetic TypeScript+JSX fixture maintained at [oxc-project/benchmark-files](https://github.com/oxc-project/benchmark-files) — to both `TestFiles::minimal()` (bench input set) and `TestFiles::complicated()` (alloc-tracking input set). The existing files in each set are untouched; this is a strict append. ## Why The existing bench input set didn't reliably surface general-purpose perf wins above the ~1-2% measurement noise floor: - #22580 (semantic pre-reserve) — visible because `binder.ts` exercises it - #22594 (formatter buffer) — visible - #22596 (minifier `try_fold_concat`) — **not visible** on the old set - #22599 (semantic resolve-refs no-temp-Vec) — **not visible** - #22603 (semantic var-hoist SmallVec) — **not visible** The kitchen-sink fixes that by exercising every AST node, every transformer plugin, every minifier optimization opportunity, and every semantic step in one large file. Verified by re-benching #22596 against this fixture: **minifier mean −1.5%, min −3.7%** — above noise, signal confirmed. ## Fixture stats (cross-checked locally) | Metric | Value | |---|---| | Source size | 21,117 lines / 732.90 kB | | AST nodes | ~133,000 | | Scopes | ~4,750 | | Symbols | ~7,000 | | Resolved references | ~16,000 | | Semantic diagnostics | 0 errors / 0 warnings | ## Snap baselines `tasks/track_memory_allocations/allocs_*.snap` updated with the kitchen-sink row across all 5 pipelines (parser / semantic / transformer / minifier / formatter). Future PRs that change allocation behavior on this fixture will produce a snap diff in CI. ## Bench-cleaner fix `tasks/benchmark/benches/lexer.rs`'s `SourceCleaner` was missing `visit_ts_template_literal_type` — TypeScript type-level template literals (e.g. `` `${T}-${U}` `` in conditional / mapped types) are syntactically identical to value-level template literals, so the bench-mode lexer (without parser context) cannot distinguish them. Without the cleaner converting them to plain strings, kitchen-sink's type-level templates caused the lexer bench to swallow ~1 KB spans as a single `TemplateHead` and produce spurious "Unterminated string" / "Invalid Unicode escape" errors. One-line fix to mirror the existing `visit_template_literal` handling. AI disclosure: drafted with Claude Code, reviewed manually.
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…ec (#22599) ## Summary `SemanticBuilder::resolve_references_for_current_scope` is the early-resolution hook fired at function / arrow / catch boundaries — it resolves the references collected since a checkpoint against the outer scope chain so that e.g. `function f(x = outerRef) {}` correctly binds `outerRef` to the outer scope rather than the function body. The old implementation copied the pending slice into a fresh `Vec` on every call: ```rust let refs = self.unresolved_references.slice_from(checkpoint).to_vec(); self.unresolved_references.truncate(checkpoint); for (name, reference_id) in refs { ... } ``` The `to_vec()` is a fresh heap allocation, needed because `walk_up_resolve_reference` takes `&mut self` and would otherwise alias the borrow on the underlying `Vec<(Ident, ReferenceId)>`. Rewrite in-place with a retain-style write cursor — each `(Ident, ReferenceId)` is read by **value** (both are `Copy`), which detaches it from the borrow on the inner Vec. Unresolved refs are compacted forward; resolved refs are dropped via the final `truncate`. No temporary `Vec`, no allocation, **no `unsafe`** — safe bounds-checked indexing via new `get` / `set` methods on `UnresolvedReferences`. ```rust let mut write_idx = checkpoint; for read_idx in checkpoint..end { let (name, reference_id) = self.unresolved_references.get(read_idx); if !self.walk_up_resolve_reference(name, reference_id) { if write_idx != read_idx { self.unresolved_references.set(write_idx, name, reference_id); } write_idx += 1; } } self.unresolved_references.truncate(write_idx); ``` ## Allocation impact `cargo allocs`, `allocs_semantic.snap` (baseline = parent commit, after var-hoist landed): | File | Size | Sys allocs before | Sys allocs after | Δ | |---|---|---|---|---| | `checker.ts` | 2.92 MB | 2,309 | **53** | **−2,256 (−98%)** | | `App.tsx` | 415 kB | 174 | **35** | **−139 (−80%)** | | `binder.ts` | 193 kB | 196 | **19** | **−177 (−90%)** | | `kitchen-sink.tsx` | 733 kB | 1,320 | **290** | **−1,030 (−78%)** | | `pdf.mjs` | 567 kB | 1,366 | 1,355 | −11 | | `antd.js` | 6.69 MB | 1,072 | 1,072 | 0 (ES5 bundled code rarely closes over outer scope from function params) | | `RadixUI.jsx` | 2.5 kB | 10 | 10 | 0 | ## How I found this After [#22580](#22580) and [#22590](#22590) the remaining semantic sys allocs were unexplained. Ran a backtrace-capturing `System` allocator wrapper on `checker.ts` and aggregated allocations by call stack — the overwhelming majority of captured allocations converged on a single site: ``` oxc_semantic::builder::SemanticBuilder::resolve_references_for_current_scope oxc_semantic::builder::SemanticBuilder as ...::Visit::visit_function ... ``` Tracing back to the `slice_from(checkpoint).to_vec()` line and confirming that the entire allocation pattern disappears with the in-place rewrite. ## Why this matters for downstream consumers `resolve_references_for_current_scope` fires once per function / arrow / catch — for normal TS / TSX code that's hundreds to thousands of calls per build. Each call was a fresh heap allocation; eliminating them removes that allocator pressure entirely. For rolldown's preprocessing pipeline (which builds semantic 3-4 times per file across hundreds of files per bundle), the per-build savings compound. ## No behavior change The in-place algorithm preserves the original semantics exactly: `unresolved_references[..checkpoint]` is untouched, and `[checkpoint..]` is the list of refs that didn't resolve, in their original order. Same as the old code. ## Test Plan - [x] `cargo test -p oxc_semantic --lib --tests` — pass - [x] `cargo allocs` — semantic snapshot updated to reflect the reductions AI disclosure: drafted with Claude Code, reviewed manually.
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### 🚀 Features - e857b0c napi/minify: Expose legalComments option and result (#20370) (Boshen) - 661132d parser: More friendly error messages for rest assignment target and rest binding element (#22719) (sapphi-red) - ee659b6 transformer/legacy-decorator: Add `strictNullChecks` option for nullable-union design:type (#22266) (Kyle Cannon) ### 🐛 Bug Fixes - e1d064e transformer/class-properties: Reparent lifted private method helpers (#22716) (Cameron) - 4ac0fca minifier: Preserve `0 && (module.exports = { ... })` cjs-module-lexer hint (#22729) (Dunqing) - 40ff611 minifier: Mark peephole loop changed when dropping dead-after-throw statement (#22722) (Dunqing) - 2f7b210 codegen: Emit pife-arrow/function leading comments inside the wrap (#22720) (Dunqing) - e184f74 parser: Improve invalid `import` property access diagnostic (#22693) (camc314) - 7baed9c transformer/private-method: Clear inherited strict flags (#22508) (camc314) - a9ad27e parser: Keep annotation comments leading without preceding newline (#22711) (Dunqing) - 9ea4d64 minifier: Re-evaluate pure/no-side-effects flags after peephole inlining (#22595) (Dunqing) - 07afbb6 minifier: Drop empty-body IIFE wrapper when called with arguments (#22589) (Dunqing) - fa7c463 semantic: Correct TS enum member symbol spans (#22689) (camc314) - 26b9396 semantic: Resolve parameter decorators outside parameter scope (#22623) (camc314) - b284045 parser: Switch to module goal eagerly on `export` (#22684) (Boshen) - dfa931d semantic: Propagate unresolved auto-increment enum value instead of defaulting to 0 (#22646) (Dunqing) - 69a6ba6 transformer/legacy-decorator: Emit Array for ReadonlyArray<T> in decorator metadata (#22265) (Kyle Cannon) - e421ef0 transformer/legacy-decorator: Return runtime binding for design:type (#22640) (Dunqing) - d61e1d7 codegen: Preserve verbatim text of pure/no-side-effects comments (#22525) (Dunqing) - 702b14e minifier: Preserve IIFE structure in DCE-only mode (#22547) (Dunqing) - 917da24 parser: Apply PURE comment through member-access chains (#22566) (Dunqing) - a069b1c codegen: Preserve quotes for cjs-module-lexer equality strings (#22551) (Dunqing) ### ⚡ Performance - 2f623b0 semantic: Skip unresolved checks for re-exports (#22660) (camc314) - 0d9553d semantic: Early-exit `check_object_expression` for objects with <2 properties (#22668) (Dunqing) - d721ad9 semantic: Use direct grandparent lookup for TS type parameters (#22658) (camc314) - 0aff288 semantic: Reorder numeric literal strict mode checks (#22657) (camc314) - 4d5ddb1 semantic: Reorder binding identifier checks (#22656) (camc314) - e32acd8 semantic: Reorder identifier ambient binding check (#22653) (camc314) - 09fe178 semantic: Reorder ident reference strict mode check (#22652) (camc314) - 4b6add2 semantic: Avoid duplicate ident clone for bindings (#22663) (camc314) - 82f9662 parser: Check identifier kind before context flag (#22662) (camc314) - d7cd951 parser: Fast path identifier parsing and inline operator helpers (#22650) (Boshen) - 7b84314 semantic: Use direct byte access for numeric leading-zero check (#22642) (camc314) - 0345a31 semantic: Pre-size class elements hash map (#22618) (camc314) - 04d3065 minifier: Drop per-call buffers in try_fold_concat (#22596) (Dunqing) - 4f289f1 semantic: Resolve_references_for_current_scope without a temp Vec (#22599) (Dunqing) - e862c15 semantic: Avoid heap alloc for var hoist scope ids (#22603) (Dunqing) - 8ff8674 semantic: Early return if `excess` is `0` in `Stats::increase_by` (#22616) (camc314) - 7a4120e semantic: Pre-reserve unresolved_references using Stats::references (#22580) (Dunqing) Co-authored-by: Dunqing <29533304+Dunqing@users.noreply.github.com>

Summary
SemanticBuilder::resolve_references_for_current_scopeis the early-resolution hook fired at function / arrow / catch boundaries — it resolves the references collected since a checkpoint against the outer scope chain so that e.g.function f(x = outerRef) {}correctly bindsouterRefto the outer scope rather than the function body.The old implementation copied the pending slice into a fresh
Vecon every call:The
to_vec()is a fresh heap allocation, needed becausewalk_up_resolve_referencetakes&mut selfand would otherwise alias the borrow on the underlyingVec<(Ident, ReferenceId)>.Rewrite in-place with a retain-style write cursor — each
(Ident, ReferenceId)is read by value (both areCopy), which detaches it from the borrow on the inner Vec. Unresolved refs are compacted forward; resolved refs are dropped via the finaltruncate. No temporaryVec, no allocation, nounsafe— safe bounds-checked indexing via newget/setmethods onUnresolvedReferences.Allocation impact
cargo allocs,allocs_semantic.snap(baseline = parent commit, after var-hoist landed):checker.tsApp.tsxbinder.tskitchen-sink.tsxpdf.mjsantd.jsRadixUI.jsxHow I found this
After #22580 and #22590 the remaining semantic sys allocs were unexplained. Ran a backtrace-capturing
Systemallocator wrapper onchecker.tsand aggregated allocations by call stack — the overwhelming majority of captured allocations converged on a single site:Tracing back to the
slice_from(checkpoint).to_vec()line and confirming that the entire allocation pattern disappears with the in-place rewrite.Why this matters for downstream consumers
resolve_references_for_current_scopefires once per function / arrow / catch — for normal TS / TSX code that's hundreds to thousands of calls per build. Each call was a fresh heap allocation; eliminating them removes that allocator pressure entirely.For rolldown's preprocessing pipeline (which builds semantic 3-4 times per file across hundreds of files per bundle), the per-build savings compound.
No behavior change
The in-place algorithm preserves the original semantics exactly:
unresolved_references[..checkpoint]is untouched, and[checkpoint..]is the list of refs that didn't resolve, in their original order. Same as the old code.Test Plan
cargo test -p oxc_semantic --lib --tests— passcargo allocs— semantic snapshot updated to reflect the reductionsAI disclosure: drafted with Claude Code, reviewed manually.